Inorganic Chemistry, Vol. 17, No. 6, 1978 1681
i\otes
stereochemical rigidity of CF3SF3at ambient temperature. The fact that JFscis slightly larger than JFaScmay be a reflection of the tact that the equatorial plane of a trigonal bipyramid features more sulfur 3s character than the axes. T h e differences in the axial and equatorial F-S-C couplings may b e useful for the stereochemical assay of fluorosulfuranes. Acknowledgment. T h e authors are grateful to the Office of N a v a l Research (Contract N00014-76-(20577, T a s k No. NR 053-612) for financial support. Gratitude is also expressed to the Jet Propulsion Laboratory, Pasadena, Calif., for the loan of t h e Varian A 5 6 / 6 0 NMR spectrometer. Registry No. CF3SSCF3, 372-64-5; F2, 7782-41-4; C F S S F ~ , 374-10-7.
References and Notes (1) (a) E. A. Tyczkowski and L. A. Bigelow, J . Am. Chem. SOC.,75,3523 (1953); (b) W. A. Sheppard, ibid., 84, 3058 (1962); (c) C. T. Ratcliffe and J. M. Shreeve, ibid., 90, 5403 (1968). (2) G. H. Sprenger and A. H. Cowley, J . Fluorine Chem., 7 , 333 (1976). (3) For a summary of this controversy, see R. G.Cavell, J. A. Gibson, and K. I. The, J . Am. Chem. SOC.,99, 7841 (1977). (4) For previous I9F NMR data on CF3SF3at ambient temperature or below, see (a) ref I C and (b) W. Gombler and R. Budenz, J . Fluorine Chem.,
7, 115 (1976), and references therein.
(5) W. G. Klemperer, J. K. Krieger, M. D. McCreary, E. L. Muetterties, D. D. Traficante, and G. M. Whitesides, J . Am. Chem. SOC., 97, 7023
(1975), and references therein. Maraschin, B. D. Catsikis, L. H. Davis, G.Jarvinen, and R. J. Lagow, J . Am. Chem. SOC.,97, 5 13 (1 975). (7) For phosphoranes the order of apicophilicity is (in part) F > C1 > Br > CF3 > alkyl. See ref 3. ( 6 ) N. J.
Contribution from the Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada
Preparation and Raman Spectra of Tribromosulfur(1V) Hexafluoroarsenate(V) and Hexafluoroantimonate(V), (SBr,) +(AsF6)- and (SBr3)+(SbF6)Jack Passmore,* E. Keith Richardson, and Peter Taylor Received October 28, 1977
Sulfur tetrachloride is stable only in the solid phase (mp -30 “ C ) , binary sulfur bromides are less stable than their corresponding chlorides, and a t the present there is no evidence for sulfur t e t r a b r ~ m i d e . ’ However, ~~ OSBr2,2,4 has been well characterized a n d a number of salts with cations of the type R2SBr+ a r e known.5 T h e cations SF3+6and SC13+7with weakly basic anions such as AsF6- a n d SbF6- are well established. We now report the preparation and characterization by Raman spectroscopy of (SBr3)+(AsF6)- and (SBr3)+ (SbF6)-.
Experimental Section Apparatus. Except where stated, apparatus and materials are the same as those described in ref 8. Raman spectra were obtained with exciting wavelengths 5145 8, (green) and 6471 8, (red). Reagents. Reagent grade sulfur (B. D. H. Chemicals) was evacuated to dryness. Bromine (Matheson Gas Co.) was stored over tetraphosphorus decaoxide (P,Ol0) in a glass vessel until ready for use. Sulfur dioxide (Matheson Gas Co.) was stored over calcium hydride in a glass vessel. Antimony pentafluoride (Ozark-Mahoning) was twice distilled before use. Spectra. All solid Raman samples were loaded into dry melting point capillaries in a drybox and flame sealed immediately on removing from the drybox. Solution samples were prepared in 5-mm 0.d. glass tubing using either sulfur dioxide or arsenic trifluoride as the solvent and then sealed. Solution Raman spectra were obtained at room temperature with the 6471-8, (red) line and at a temperature just low enough to prevent bubbling with the 5145-8, (green) line, using an evacuated condenser type low temperature cell. 0020-1669/78/ 1317-168 l$Ol .OO/O
Reactions. All reactions were carried out in a one-piece glass apparatus, consisting of two arms linked by a tube incorporating a sintered-glass filter disk. One arm was fitted with a Teflon “Rotaflo” or a Whitey 1KS4 valve. Typically sulfur was loaded into one arm of the apparatus, which was then evacuated, and the solvent (SO2 or AsF,), bromine, and then AsF, or SbF, were condensed in separately at -196 OC (with thermal cycling to room temperature between each addition). Preparation of (SBr,)+(AsF,)-. In a typical reaction, sa(0.703 mmol) and Br2 (26.65 mmol) were allowed to react with AsF5 (10.65) mmol) in sulfur dioxide (5.95 g) solution. The product was a saturated purple solution with a copious yellow precipitate. The soluble product was isolated by repeated washings through the frit. The volatiles were identified as a mixture of SOz, some AsF, containing traces of AsF, from infrared spectra. A light yellow insoluble solid (0.02 g) and a bright yellow soluble solid (2.405 g or 5.22 mmol assuming (SBr,)+(AsF,)-) were isolated following removal of the volatiles with brief pumping. A chemical analysis of the product was not obtained since it gave off bromine on standing in a sealed glass sample tube in an atmosphere of dry nitrogen. Raman spectra were obtained from the yellow soluble product in the solid state and in both arsenic trifluoride and sulfur dioxide solutions using both exciting wavelengths. Preparation of (sBr,)+(sbF,)-. In a typical reaction sa(0.86 mmol) and Br2 (1 1.06 mmol) were allowed to react with SbF5 (1 1.63 mmol) in sulfur dioxide (5.76 g) solution. The product was a saturated purple solution with a copious yellow precipitate. The soluble product was separated by repeated washings through the frit. The volatiles were removed leaving 0.828 g of an insoluble white solid and 3.302 g or 6.50 mmol (assuming (SBr,)+(SbF,)-) of soluble yellow crystalline solid. The yellow solid gave elemental analysis consistent with the formulation (SBr3)+(SbF6)-. Anal. Calcd for (SBr3)+(SbF6)-: S, 6.30; Br, 47.23; Sb, 23.99; F, 22.46. Found: S, 6.13; Br, 46.80; Sb, 24.16; F, 22.77. Raman spectra were obtained for both solids. The spectrum of the white insoluble solid is similar to that obtained when SbF3-SbF5 (A)’ was reacted with excess PF, in arsenic trifluoride solution for 2 days.I0 Raman spectra were also obtained from the yellow soluble product in the solid state and in arsenic trifluoride and sulfur dioxide solutions using both exciting wavelengths. In another experiment SB(2.52 mmol) and Br2 (30.6 mmol) were allowed to react with SbF5 (34.46 mmol) in SO2 (7.57 g) solution yielding 19.91 mmol of soluble (SBr,)+(SbFJ and 2.27 g of a reduced antimony fluoride. The products were characterized by their Raman spectra.
Results and Discussion Preparation of (SBr3)+(AsF6)-and (SBr3)+(SbF6)-. Sulfur reacts with excess bromine a n d a slight excess of AsF, in arsenic trifluoride to give a bright yellow solid (SBr3)+(AsF6)according t o the equation l/&,
+ 3Br, + 3AsF,
-+
2(SBr,)+(AsF,)- t AsF,
T h e salt was identified from Raman spectra in the solid state, in arsenic trifluoride solution, a n d also in sulfur dioxide solution. The solid gave some bromine on standing, in a sealed glass sample tube under an atmosphere of dry nitrogen. T h e (SBr3)+(SbF6)- cation salt made in a similar fashion was stable and good analyses were obtained. T h e nature of the insoluble reduced antimony fluoride product given in the S8/Br2/SbF5 reaction is presently under investigation. Elemental analysis and Raman spectroscopy were used to characterize t h e (SBr3)+(SbF6)-. We note that the analogous reactions with iodine and sulfur lead to S71+containing salts” and related species; whereas SeBr3+and TeBr3+ can be m a d e in a similar manner.12 Raman Spectra. Raman spectra of (SBr3)+(AsF6)- a n d (SBr3)+(SbF6)- in t h e solid state a n d in solution are given in Figure 1, and T a b l e I lists t h e frequencies a n d assignments by comparison with t h e corresponding anions6.l3a n d PBr3.I4 Solvent peaks15J6 and a weak peak at 319 cm-l observed in t h e solution spectra a n d attributed to bromine1’ a r e not included in Table I. 0 1978 American Chemical Society
1682 Inorganic Chemistry, Vol. 17, No. 6, 1978 Table I. Assignments of Raman Spectra’ of (SBr,)’(AsF,)-
,
(SBr )‘(AsF,)Solid AsF, s o h
(SBr,)+(SbF,)Solid so, soh
130gb 872.5 685 sh 674 573 562
676 560 436 p
429 414 39 1 367.5 375 175 128
421 d p
378.5 p 174 p 124 d p
Notes and (SBr,)+(SbF,)PBr,‘ gas
(SF,h+(As-
F6)- solid C S A S F , ~ LiSbF,e
Assignment
867.5 675 sh 642 562.5
643.5 560 434 p 417 d p
42 1 41 0.5 277
711 68 6
:ii
400
280h
379 175 127.5
376.5 p 175.5 p 124 d p
38 1 161 116
685 576
668 558
Iu,(MF,)-
372
294
IY,(MF,)- or us(MF,)v 4 (MF, 1-
922
iii
942 5 34 40 3
(SBr3)’ v, (SBr,)+ v4(SBr,)l Frequencies (in cm-’) accurate to ca. i 2 cm-’. See a Solvent peaks and Br, stretch omitted. These are, however, marked in Figure 1. Correref 14. See ref 6. e See ref 13. Tentative assignment assuming Oh and C, symmetry for (MF,)- (M = A s or Sb) and (SEI,)+. Could b e an impurity. sponds t o u3(PBr,) o r v3(SF3)I in appropriate column. VI
‘
b I I
I
I
‘ IL I
broadened in the order 436 > 872 > 1309 cm-’ and therefore is likely a resonance R a m a n spectrum. It was least intense for (SBr3)+(SbF6)-in sulfur dioxide solution using the 6471-A (red) exciting frequency and no overtones were observed. W e are presently attempting to determine the nature of this species. Acknowledgment. W e thank the National Research Council of C a n a d a for financial support and a fellowship (E.K.R.). Registry No. (SBr3)+(AsF6)-,66142-09-4; (SBr3)+(SbF6)-, 66142-10-7.
References and Kotes 0. Ruff, Chem. Ber., 37, 4513 (1904). J. W. Mellow, “Comprehensive Inorganic and Theoretical Chemistry”, Vol. X, Longman and Green, London, 1930, pp 646-647. F. A. Cotton and G. Wilkinson, “Advanced Inorganic Chemistry”, 3rd ed, Wiley, Toronto, 1972, pp 437, 440. H. A . Mayes and J. R. Pardington, J . Chem. Soc., 2594 (1926). J. P. Marino in “Topics in Sulfur Chemistry”, Vol. I , A. Senning, Ed., G. Thieme. Stutteart. 1976. OD 51-53. and references therein. D. D. Gibler, C. J.kdarns, M.’&cher, A. Zalkin, and N. Bartlett, Inorg. Chem., 11, 2325 (1972). W. Sawodny and K. Dehnicke, Z . Anorg. Allg. Chem., 349, 169 (1967), and references therein. J. Passmore and P. Taylor, J . Chem. Soc., Dalton Trans.,804 (1976). T. Birchall, P. A. W. Dean, B. Della Valle, and R. J. Gillespie, Can. J . Chem., 51, 667 (1973). J. Passmore and P. Taylor, 1976, unpublished data. J . Passmore, P. Taylor, T. K. Whidden, and P. White, J . Chem. Soc., Chem. Commun., 689 (1976). J . Passmore and E. K. Richardson, 1976, unpublished data. G. M. Begun and A. C. Rutenburg, Inorg. Chem., 6, 2212 (1967). A. T. Kozulin, A. V. Gogolev, V. I. Karmanov, and V. A. Murtsovkin, Opt. Spektrosk., 44, 1218 (1973). J. A. Evans and D. A. Long, J . Chem. SOC.A , 1688 (1968). G. Herzberg, “Molecular Spectra and Molecular Structure”, Val. 11, Van Kostrand, New York, N.Y., 1945, p 285. H.Stammreich, R. Forneris, and Y. Tavares, Spectrochim. Acta, 17, 1173 11961). C. La;, H. Lynton, J. Passmore, and P. Y . Sew, J . Chem. Soc.. Dalton Trans., 2535 (1973). ~~
1300 900
700
I
1
I
500
300
100
F R E 0 U E N C Y (c m -I)
Figure 1. R a m a n spectra of t h e (SBr3)+ cation: (a) solid (SBr3)+(SbF6)-(6471-A line); (b) solid (SBr3)+(AsF6)-(5145-A line); (c) (SBr3)+(SbF6)-in SO2 solution (5 145-A line); (d) (SBr3)+(AsF6)in AsF3 solution (5145-A line). Slit width 8 cm-’ except in (b), which was a t 4 cm-’. X indicates solvent peaks. 0 indicates t h e Br, peak. indicates impurities.
+
T h e spectra support a n essentially ionic formulation for the two salts. The peaks attributed to SBr,’ are similar in solution a n d in the solid state, except LJ, (SBr,’), the antisymmetric stretching mode, (e), is split in the solid state. The four Raman active bands (two polarized and two depolarized) expected for S B r 3 + a r e observed, and as expected,6,18they a r e a t higher frequencies than the corresponding bands for the isoelectronic molecule PBr3 except for v l (SBr,’) which is not significantly different f r o m v , (PBr,). T h e peaks designated v ( X ) in Table I were observed in solution spectra and varied in intensity from sample to sample. T h e most intense was observed for (SBr,)+(AsF,)- made in situ in arsenic trifluoride and (SBr3)+(SbF6)-in dilute sulfur dioxide or arsenic trifluoride solution with the 5 145-A (green) exciting wavelength. T h e intensity decreased, and the peak
Contribution f r o m t h e Chemistry Department, University of Tasmania, H o b a r t , Tasmania, 7001, Australia
Polarized Crystal Electronic Spectrum of Bis(ethy1ammonium) Tetrachlorocuprate(I1) and an Application of the Angular Overlap Model to the Bonding in Chlorocuprate Complexes Michael A. H i t c h m a n * a n d Peter J. Cassidy Receiced October 24, I977
T h e chlorocuprates exhibit a wide variety of stereochemistries and it is probably for this reason that they have often
0020-1669/78/ 13 17-1682$01 .OO/O @ 1978 American Chemical Society
